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qemu-e2k/block/qcow2-refcount.c
John Snow 9533423063 qcow2: avoid misaligned 64bit bswap 
If we create a buffer directly on the stack by using 12 bytes, there's
no guarantee the 64bit value we want to swap will be aligned, which
could cause errors with undefined behavior.

Spotted with clang -fsanitize=undefined and observed in iotests 15, 26,
44, 115 and 121.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-11-11 16:25:47 +01:00

2470 lines
83 KiB
C
Raw Blame History

/*
* Block driver for the QCOW version 2 format
*
* Copyright (c) 2004-2006 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "block/block_int.h"
#include "block/qcow2.h"
#include "qemu/range.h"
static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size);
static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length, uint64_t addend,
bool decrease, enum qcow2_discard_type type);
static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index);
static void set_refcount_ro0(void *refcount_array, uint64_t index,
uint64_t value);
static void set_refcount_ro1(void *refcount_array, uint64_t index,
uint64_t value);
static void set_refcount_ro2(void *refcount_array, uint64_t index,
uint64_t value);
static void set_refcount_ro3(void *refcount_array, uint64_t index,
uint64_t value);
static void set_refcount_ro4(void *refcount_array, uint64_t index,
uint64_t value);
static void set_refcount_ro5(void *refcount_array, uint64_t index,
uint64_t value);
static void set_refcount_ro6(void *refcount_array, uint64_t index,
uint64_t value);
static Qcow2GetRefcountFunc *const get_refcount_funcs[] = {
&get_refcount_ro0,
&get_refcount_ro1,
&get_refcount_ro2,
&get_refcount_ro3,
&get_refcount_ro4,
&get_refcount_ro5,
&get_refcount_ro6
};
static Qcow2SetRefcountFunc *const set_refcount_funcs[] = {
&set_refcount_ro0,
&set_refcount_ro1,
&set_refcount_ro2,
&set_refcount_ro3,
&set_refcount_ro4,
&set_refcount_ro5,
&set_refcount_ro6
};
/*********************************************************/
/* refcount handling */
int qcow2_refcount_init(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
unsigned int refcount_table_size2, i;
int ret;
assert(s->refcount_order >= 0 && s->refcount_order <= 6);
s->get_refcount = get_refcount_funcs[s->refcount_order];
s->set_refcount = set_refcount_funcs[s->refcount_order];
assert(s->refcount_table_size <= INT_MAX / sizeof(uint64_t));
refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
s->refcount_table = g_try_malloc(refcount_table_size2);
if (s->refcount_table_size > 0) {
if (s->refcount_table == NULL) {
ret = -ENOMEM;
goto fail;
}
BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD);
ret = bdrv_pread(bs->file->bs, s->refcount_table_offset,
s->refcount_table, refcount_table_size2);
if (ret < 0) {
goto fail;
}
for(i = 0; i < s->refcount_table_size; i++)
be64_to_cpus(&s->refcount_table[i]);
}
return 0;
fail:
return ret;
}
void qcow2_refcount_close(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
g_free(s->refcount_table);
}
static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index)
{
return (((const uint8_t *)refcount_array)[index / 8] >> (index % 8)) & 0x1;
}
static void set_refcount_ro0(void *refcount_array, uint64_t index,
uint64_t value)
{
assert(!(value >> 1));
((uint8_t *)refcount_array)[index / 8] &= ~(0x1 << (index % 8));
((uint8_t *)refcount_array)[index / 8] |= value << (index % 8);
}
static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index)
{
return (((const uint8_t *)refcount_array)[index / 4] >> (2 * (index % 4)))
& 0x3;
}
static void set_refcount_ro1(void *refcount_array, uint64_t index,
uint64_t value)
{
assert(!(value >> 2));
((uint8_t *)refcount_array)[index / 4] &= ~(0x3 << (2 * (index % 4)));
((uint8_t *)refcount_array)[index / 4] |= value << (2 * (index % 4));
}
static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index)
{
return (((const uint8_t *)refcount_array)[index / 2] >> (4 * (index % 2)))
& 0xf;
}
static void set_refcount_ro2(void *refcount_array, uint64_t index,
uint64_t value)
{
assert(!(value >> 4));
((uint8_t *)refcount_array)[index / 2] &= ~(0xf << (4 * (index % 2)));
((uint8_t *)refcount_array)[index / 2] |= value << (4 * (index % 2));
}
static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index)
{
return ((const uint8_t *)refcount_array)[index];
}
static void set_refcount_ro3(void *refcount_array, uint64_t index,
uint64_t value)
{
assert(!(value >> 8));
((uint8_t *)refcount_array)[index] = value;
}
static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index)
{
return be16_to_cpu(((const uint16_t *)refcount_array)[index]);
}
static void set_refcount_ro4(void *refcount_array, uint64_t index,
uint64_t value)
{
assert(!(value >> 16));
((uint16_t *)refcount_array)[index] = cpu_to_be16(value);
}
static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index)
{
return be32_to_cpu(((const uint32_t *)refcount_array)[index]);
}
static void set_refcount_ro5(void *refcount_array, uint64_t index,
uint64_t value)
{
assert(!(value >> 32));
((uint32_t *)refcount_array)[index] = cpu_to_be32(value);
}
static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index)
{
return be64_to_cpu(((const uint64_t *)refcount_array)[index]);
}
static void set_refcount_ro6(void *refcount_array, uint64_t index,
uint64_t value)
{
((uint64_t *)refcount_array)[index] = cpu_to_be64(value);
}
static int load_refcount_block(BlockDriverState *bs,
int64_t refcount_block_offset,
void **refcount_block)
{
BDRVQcow2State *s = bs->opaque;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD);
ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
refcount_block);
return ret;
}
/*
* Retrieves the refcount of the cluster given by its index and stores it in
* *refcount. Returns 0 on success and -errno on failure.
*/
int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index,
uint64_t *refcount)
{
BDRVQcow2State *s = bs->opaque;
uint64_t refcount_table_index, block_index;
int64_t refcount_block_offset;
int ret;
void *refcount_block;
refcount_table_index = cluster_index >> s->refcount_block_bits;
if (refcount_table_index >= s->refcount_table_size) {
*refcount = 0;
return 0;
}
refcount_block_offset =
s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK;
if (!refcount_block_offset) {
*refcount = 0;
return 0;
}
if (offset_into_cluster(s, refcount_block_offset)) {
qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" PRIx64
" unaligned (reftable index: %#" PRIx64 ")",
refcount_block_offset, refcount_table_index);
return -EIO;
}
ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
&refcount_block);
if (ret < 0) {
return ret;
}
block_index = cluster_index & (s->refcount_block_size - 1);
*refcount = s->get_refcount(refcount_block, block_index);
qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
return 0;
}
/*
* Rounds the refcount table size up to avoid growing the table for each single
* refcount block that is allocated.
*/
static unsigned int next_refcount_table_size(BDRVQcow2State *s,
unsigned int min_size)
{
unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1;
unsigned int refcount_table_clusters =
MAX(1, s->refcount_table_size >> (s->cluster_bits - 3));
while (min_clusters > refcount_table_clusters) {
refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2;
}
return refcount_table_clusters << (s->cluster_bits - 3);
}
/* Checks if two offsets are described by the same refcount block */
static int in_same_refcount_block(BDRVQcow2State *s, uint64_t offset_a,
uint64_t offset_b)
{
uint64_t block_a = offset_a >> (s->cluster_bits + s->refcount_block_bits);
uint64_t block_b = offset_b >> (s->cluster_bits + s->refcount_block_bits);
return (block_a == block_b);
}
/*
* Loads a refcount block. If it doesn't exist yet, it is allocated first
* (including growing the refcount table if needed).
*
* Returns 0 on success or -errno in error case
*/
static int alloc_refcount_block(BlockDriverState *bs,
int64_t cluster_index, void **refcount_block)
{
BDRVQcow2State *s = bs->opaque;
unsigned int refcount_table_index;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
/* Find the refcount block for the given cluster */
refcount_table_index = cluster_index >> s->refcount_block_bits;
if (refcount_table_index < s->refcount_table_size) {
uint64_t refcount_block_offset =
s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK;
/* If it's already there, we're done */
if (refcount_block_offset) {
if (offset_into_cluster(s, refcount_block_offset)) {
qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#"
PRIx64 " unaligned (reftable index: "
"%#x)", refcount_block_offset,
refcount_table_index);
return -EIO;
}
return load_refcount_block(bs, refcount_block_offset,
refcount_block);
}
}
/*
* If we came here, we need to allocate something. Something is at least
* a cluster for the new refcount block. It may also include a new refcount
* table if the old refcount table is too small.
*
* Note that allocating clusters here needs some special care:
*
* - We can't use the normal qcow2_alloc_clusters(), it would try to
* increase the refcount and very likely we would end up with an endless
* recursion. Instead we must place the refcount blocks in a way that
* they can describe them themselves.
*
* - We need to consider that at this point we are inside update_refcounts
* and potentially doing an initial refcount increase. This means that
* some clusters have already been allocated by the caller, but their
* refcount isn't accurate yet. If we allocate clusters for metadata, we
* need to return -EAGAIN to signal the caller that it needs to restart
* the search for free clusters.
*
* - alloc_clusters_noref and qcow2_free_clusters may load a different
* refcount block into the cache
*/
*refcount_block = NULL;
/* We write to the refcount table, so we might depend on L2 tables */
ret = qcow2_cache_flush(bs, s->l2_table_cache);
if (ret < 0) {
return ret;
}
/* Allocate the refcount block itself and mark it as used */
int64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
if (new_block < 0) {
return new_block;
}
#ifdef DEBUG_ALLOC2
fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
" at %" PRIx64 "\n",
refcount_table_index, cluster_index << s->cluster_bits, new_block);
#endif
if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) {
/* Zero the new refcount block before updating it */
ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block,
refcount_block);
if (ret < 0) {
goto fail_block;
}
memset(*refcount_block, 0, s->cluster_size);
/* The block describes itself, need to update the cache */
int block_index = (new_block >> s->cluster_bits) &
(s->refcount_block_size - 1);
s->set_refcount(*refcount_block, block_index, 1);
} else {
/* Described somewhere else. This can recurse at most twice before we
* arrive at a block that describes itself. */
ret = update_refcount(bs, new_block, s->cluster_size, 1, false,
QCOW2_DISCARD_NEVER);
if (ret < 0) {
goto fail_block;
}
ret = qcow2_cache_flush(bs, s->refcount_block_cache);
if (ret < 0) {
goto fail_block;
}
/* Initialize the new refcount block only after updating its refcount,
* update_refcount uses the refcount cache itself */
ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block,
refcount_block);
if (ret < 0) {
goto fail_block;
}
memset(*refcount_block, 0, s->cluster_size);
}
/* Now the new refcount block needs to be written to disk */
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE);
qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache, *refcount_block);
ret = qcow2_cache_flush(bs, s->refcount_block_cache);
if (ret < 0) {
goto fail_block;
}
/* If the refcount table is big enough, just hook the block up there */
if (refcount_table_index < s->refcount_table_size) {
uint64_t data64 = cpu_to_be64(new_block);
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP);
ret = bdrv_pwrite_sync(bs->file->bs,
s->refcount_table_offset + refcount_table_index * sizeof(uint64_t),
&data64, sizeof(data64));
if (ret < 0) {
goto fail_block;
}
s->refcount_table[refcount_table_index] = new_block;
/* The new refcount block may be where the caller intended to put its
* data, so let it restart the search. */
return -EAGAIN;
}
qcow2_cache_put(bs, s->refcount_block_cache, refcount_block);
/*
* If we come here, we need to grow the refcount table. Again, a new
* refcount table needs some space and we can't simply allocate to avoid
* endless recursion.
*
* Therefore let's grab new refcount blocks at the end of the image, which
* will describe themselves and the new refcount table. This way we can
* reference them only in the new table and do the switch to the new
* refcount table at once without producing an inconsistent state in
* between.
*/
BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW);
/* Calculate the number of refcount blocks needed so far; this will be the
* basis for calculating the index of the first cluster used for the
* self-describing refcount structures which we are about to create.
*
* Because we reached this point, there cannot be any refcount entries for
* cluster_index or higher indices yet. However, because new_block has been
* allocated to describe that cluster (and it will assume this role later
* on), we cannot use that index; also, new_block may actually have a higher
* cluster index than cluster_index, so it needs to be taken into account
* here (and 1 needs to be added to its value because that cluster is used).
*/
uint64_t blocks_used = DIV_ROUND_UP(MAX(cluster_index + 1,
(new_block >> s->cluster_bits) + 1),
s->refcount_block_size);
if (blocks_used > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) {
return -EFBIG;
}
/* And now we need at least one block more for the new metadata */
uint64_t table_size = next_refcount_table_size(s, blocks_used + 1);
uint64_t last_table_size;
uint64_t blocks_clusters;
do {
uint64_t table_clusters =
size_to_clusters(s, table_size * sizeof(uint64_t));
blocks_clusters = 1 +
((table_clusters + s->refcount_block_size - 1)
/ s->refcount_block_size);
uint64_t meta_clusters = table_clusters + blocks_clusters;
last_table_size = table_size;
table_size = next_refcount_table_size(s, blocks_used +
((meta_clusters + s->refcount_block_size - 1)
/ s->refcount_block_size));
} while (last_table_size != table_size);
#ifdef DEBUG_ALLOC2
fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n",
s->refcount_table_size, table_size);
#endif
/* Create the new refcount table and blocks */
uint64_t meta_offset = (blocks_used * s->refcount_block_size) *
s->cluster_size;
uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size;
uint64_t *new_table = g_try_new0(uint64_t, table_size);
void *new_blocks = g_try_malloc0(blocks_clusters * s->cluster_size);
assert(table_size > 0 && blocks_clusters > 0);
if (new_table == NULL || new_blocks == NULL) {
ret = -ENOMEM;
goto fail_table;
}
/* Fill the new refcount table */
memcpy(new_table, s->refcount_table,
s->refcount_table_size * sizeof(uint64_t));
new_table[refcount_table_index] = new_block;
int i;
for (i = 0; i < blocks_clusters; i++) {
new_table[blocks_used + i] = meta_offset + (i * s->cluster_size);
}
/* Fill the refcount blocks */
uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t));
int block = 0;
for (i = 0; i < table_clusters + blocks_clusters; i++) {
s->set_refcount(new_blocks, block++, 1);
}
/* Write refcount blocks to disk */
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS);
ret = bdrv_pwrite_sync(bs->file->bs, meta_offset, new_blocks,
blocks_clusters * s->cluster_size);
g_free(new_blocks);
new_blocks = NULL;
if (ret < 0) {
goto fail_table;
}
/* Write refcount table to disk */
for(i = 0; i < table_size; i++) {
cpu_to_be64s(&new_table[i]);
}
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE);
ret = bdrv_pwrite_sync(bs->file->bs, table_offset, new_table,
table_size * sizeof(uint64_t));
if (ret < 0) {
goto fail_table;
}
for(i = 0; i < table_size; i++) {
be64_to_cpus(&new_table[i]);
}
/* Hook up the new refcount table in the qcow2 header */
struct QEMU_PACKED {
uint64_t d64;
uint32_t d32;
} data;
cpu_to_be64w(&data.d64, table_offset);
cpu_to_be32w(&data.d32, table_clusters);
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE);
ret = bdrv_pwrite_sync(bs->file->bs,
offsetof(QCowHeader, refcount_table_offset),
&data, sizeof(data));
if (ret < 0) {
goto fail_table;
}
/* And switch it in memory */
uint64_t old_table_offset = s->refcount_table_offset;
uint64_t old_table_size = s->refcount_table_size;
g_free(s->refcount_table);
s->refcount_table = new_table;
s->refcount_table_size = table_size;
s->refcount_table_offset = table_offset;
/* Free old table. */
qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
ret = load_refcount_block(bs, new_block, refcount_block);
if (ret < 0) {
return ret;
}
/* If we were trying to do the initial refcount update for some cluster
* allocation, we might have used the same clusters to store newly
* allocated metadata. Make the caller search some new space. */
return -EAGAIN;
fail_table:
g_free(new_blocks);
g_free(new_table);
fail_block:
if (*refcount_block != NULL) {
qcow2_cache_put(bs, s->refcount_block_cache, refcount_block);
}
return ret;
}
void qcow2_process_discards(BlockDriverState *bs, int ret)
{
BDRVQcow2State *s = bs->opaque;
Qcow2DiscardRegion *d, *next;
QTAILQ_FOREACH_SAFE(d, &s->discards, next, next) {
QTAILQ_REMOVE(&s->discards, d, next);
/* Discard is optional, ignore the return value */
if (ret >= 0) {
bdrv_discard(bs->file->bs,
d->offset >> BDRV_SECTOR_BITS,
d->bytes >> BDRV_SECTOR_BITS);
}
g_free(d);
}
}
static void update_refcount_discard(BlockDriverState *bs,
uint64_t offset, uint64_t length)
{
BDRVQcow2State *s = bs->opaque;
Qcow2DiscardRegion *d, *p, *next;
QTAILQ_FOREACH(d, &s->discards, next) {
uint64_t new_start = MIN(offset, d->offset);
uint64_t new_end = MAX(offset + length, d->offset + d->bytes);
if (new_end - new_start <= length + d->bytes) {
/* There can't be any overlap, areas ending up here have no
* references any more and therefore shouldn't get freed another
* time. */
assert(d->bytes + length == new_end - new_start);
d->offset = new_start;
d->bytes = new_end - new_start;
goto found;
}
}
d = g_malloc(sizeof(*d));
*d = (Qcow2DiscardRegion) {
.bs = bs,
.offset = offset,
.bytes = length,
};
QTAILQ_INSERT_TAIL(&s->discards, d, next);
found:
/* Merge discard requests if they are adjacent now */
QTAILQ_FOREACH_SAFE(p, &s->discards, next, next) {
if (p == d
|| p->offset > d->offset + d->bytes
|| d->offset > p->offset + p->bytes)
{
continue;
}
/* Still no overlap possible */
assert(p->offset == d->offset + d->bytes
|| d->offset == p->offset + p->bytes);
QTAILQ_REMOVE(&s->discards, p, next);
d->offset = MIN(d->offset, p->offset);
d->bytes += p->bytes;
g_free(p);
}
}
/* XXX: cache several refcount block clusters ? */
/* @addend is the absolute value of the addend; if @decrease is set, @addend
* will be subtracted from the current refcount, otherwise it will be added */
static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
int64_t offset,
int64_t length,
uint64_t addend,
bool decrease,
enum qcow2_discard_type type)
{
BDRVQcow2State *s = bs->opaque;
int64_t start, last, cluster_offset;
void *refcount_block = NULL;
int64_t old_table_index = -1;
int ret;
#ifdef DEBUG_ALLOC2
fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64
" addend=%s%" PRIu64 "\n", offset, length, decrease ? "-" : "",
addend);
#endif
if (length < 0) {
return -EINVAL;
} else if (length == 0) {
return 0;
}
if (decrease) {
qcow2_cache_set_dependency(bs, s->refcount_block_cache,
s->l2_table_cache);
}
start = start_of_cluster(s, offset);
last = start_of_cluster(s, offset + length - 1);
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size)
{
int block_index;
uint64_t refcount;
int64_t cluster_index = cluster_offset >> s->cluster_bits;
int64_t table_index = cluster_index >> s->refcount_block_bits;
/* Load the refcount block and allocate it if needed */
if (table_index != old_table_index) {
if (refcount_block) {
qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
}
ret = alloc_refcount_block(bs, cluster_index, &refcount_block);
if (ret < 0) {
goto fail;
}
}
old_table_index = table_index;
qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache,
refcount_block);
/* we can update the count and save it */
block_index = cluster_index & (s->refcount_block_size - 1);
refcount = s->get_refcount(refcount_block, block_index);
if (decrease ? (refcount - addend > refcount)
: (refcount + addend < refcount ||
refcount + addend > s->refcount_max))
{
ret = -EINVAL;
goto fail;
}
if (decrease) {
refcount -= addend;
} else {
refcount += addend;
}
if (refcount == 0 && cluster_index < s->free_cluster_index) {
s->free_cluster_index = cluster_index;
}
s->set_refcount(refcount_block, block_index, refcount);
if (refcount == 0 && s->discard_passthrough[type]) {
update_refcount_discard(bs, cluster_offset, s->cluster_size);
}
}
ret = 0;
fail:
if (!s->cache_discards) {
qcow2_process_discards(bs, ret);
}
/* Write last changed block to disk */
if (refcount_block) {
qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
}
/*
* Try do undo any updates if an error is returned (This may succeed in
* some cases like ENOSPC for allocating a new refcount block)
*/
if (ret < 0) {
int dummy;
dummy = update_refcount(bs, offset, cluster_offset - offset, addend,
!decrease, QCOW2_DISCARD_NEVER);
(void)dummy;
}
return ret;
}
/*
* Increases or decreases the refcount of a given cluster.
*
* @addend is the absolute value of the addend; if @decrease is set, @addend
* will be subtracted from the current refcount, otherwise it will be added.
*
* On success 0 is returned; on failure -errno is returned.
*/
int qcow2_update_cluster_refcount(BlockDriverState *bs,
int64_t cluster_index,
uint64_t addend, bool decrease,
enum qcow2_discard_type type)
{
BDRVQcow2State *s = bs->opaque;
int ret;
ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend,
decrease, type);
if (ret < 0) {
return ret;
}
return 0;
}
/*********************************************************/
/* cluster allocation functions */
/* return < 0 if error */
static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size)
{
BDRVQcow2State *s = bs->opaque;
uint64_t i, nb_clusters, refcount;
int ret;
/* We can't allocate clusters if they may still be queued for discard. */
if (s->cache_discards) {
qcow2_process_discards(bs, 0);
}
nb_clusters = size_to_clusters(s, size);
retry:
for(i = 0; i < nb_clusters; i++) {
uint64_t next_cluster_index = s->free_cluster_index++;
ret = qcow2_get_refcount(bs, next_cluster_index, &refcount);
if (ret < 0) {
return ret;
} else if (refcount != 0) {
goto retry;
}
}
/* Make sure that all offsets in the "allocated" range are representable
* in an int64_t */
if (s->free_cluster_index > 0 &&
s->free_cluster_index - 1 > (INT64_MAX >> s->cluster_bits))
{
return -EFBIG;
}
#ifdef DEBUG_ALLOC2
fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n",
size,
(s->free_cluster_index - nb_clusters) << s->cluster_bits);
#endif
return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
}
int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size)
{
int64_t offset;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
do {
offset = alloc_clusters_noref(bs, size);
if (offset < 0) {
return offset;
}
ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
} while (ret == -EAGAIN);
if (ret < 0) {
return ret;
}
return offset;
}
int64_t qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
int64_t nb_clusters)
{
BDRVQcow2State *s = bs->opaque;
uint64_t cluster_index, refcount;
uint64_t i;
int ret;
assert(nb_clusters >= 0);
if (nb_clusters == 0) {
return 0;
}
do {
/* Check how many clusters there are free */
cluster_index = offset >> s->cluster_bits;
for(i = 0; i < nb_clusters; i++) {
ret = qcow2_get_refcount(bs, cluster_index++, &refcount);
if (ret < 0) {
return ret;
} else if (refcount != 0) {
break;
}
}
/* And then allocate them */
ret = update_refcount(bs, offset, i << s->cluster_bits, 1, false,
QCOW2_DISCARD_NEVER);
} while (ret == -EAGAIN);
if (ret < 0) {
return ret;
}
return i;
}
/* only used to allocate compressed sectors. We try to allocate
contiguous sectors. size must be <= cluster_size */
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
{
BDRVQcow2State *s = bs->opaque;
int64_t offset;
size_t free_in_cluster;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES);
assert(size > 0 && size <= s->cluster_size);
assert(!s->free_byte_offset || offset_into_cluster(s, s->free_byte_offset));
offset = s->free_byte_offset;
if (offset) {
uint64_t refcount;
ret = qcow2_get_refcount(bs, offset >> s->cluster_bits, &refcount);
if (ret < 0) {
return ret;
}
if (refcount == s->refcount_max) {
offset = 0;
}
}
free_in_cluster = s->cluster_size - offset_into_cluster(s, offset);
do {
if (!offset || free_in_cluster < size) {
int64_t new_cluster = alloc_clusters_noref(bs, s->cluster_size);
if (new_cluster < 0) {
return new_cluster;
}
if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) {
offset = new_cluster;
free_in_cluster = s->cluster_size;
} else {
free_in_cluster += s->cluster_size;
}
}
assert(offset);
ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
if (ret < 0) {
offset = 0;
}
} while (ret == -EAGAIN);
if (ret < 0) {
return ret;
}
/* The cluster refcount was incremented; refcount blocks must be flushed
* before the caller's L2 table updates. */
qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache);
s->free_byte_offset = offset + size;
if (!offset_into_cluster(s, s->free_byte_offset)) {
s->free_byte_offset = 0;
}
return offset;
}
void qcow2_free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size,
enum qcow2_discard_type type)
{
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);
ret = update_refcount(bs, offset, size, 1, true, type);
if (ret < 0) {
fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));
/* TODO Remember the clusters to free them later and avoid leaking */
}
}
/*
* Free a cluster using its L2 entry (handles clusters of all types, e.g.
* normal cluster, compressed cluster, etc.)
*/
void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
int nb_clusters, enum qcow2_discard_type type)
{
BDRVQcow2State *s = bs->opaque;
switch (qcow2_get_cluster_type(l2_entry)) {
case QCOW2_CLUSTER_COMPRESSED:
{
int nb_csectors;
nb_csectors = ((l2_entry >> s->csize_shift) &
s->csize_mask) + 1;
qcow2_free_clusters(bs,
(l2_entry & s->cluster_offset_mask) & ~511,
nb_csectors * 512, type);
}
break;
case QCOW2_CLUSTER_NORMAL:
case QCOW2_CLUSTER_ZERO:
if (l2_entry & L2E_OFFSET_MASK) {
if (offset_into_cluster(s, l2_entry & L2E_OFFSET_MASK)) {
qcow2_signal_corruption(bs, false, -1, -1,
"Cannot free unaligned cluster %#llx",
l2_entry & L2E_OFFSET_MASK);
} else {
qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,
nb_clusters << s->cluster_bits, type);
}
}
break;
case QCOW2_CLUSTER_UNALLOCATED:
break;
default:
abort();
}
}
/*********************************************************/
/* snapshots and image creation */
/* update the refcounts of snapshots and the copied flag */
int qcow2_update_snapshot_refcount(BlockDriverState *bs,
int64_t l1_table_offset, int l1_size, int addend)
{
BDRVQcow2State *s = bs->opaque;
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, refcount;
bool l1_allocated = false;
int64_t old_offset, old_l2_offset;
int i, j, l1_modified = 0, nb_csectors;
int ret;
assert(addend >= -1 && addend <= 1);
l2_table = NULL;
l1_table = NULL;
l1_size2 = l1_size * sizeof(uint64_t);
s->cache_discards = true;
/* WARNING: qcow2_snapshot_goto relies on this function not using the
* l1_table_offset when it is the current s->l1_table_offset! Be careful
* when changing this! */
if (l1_table_offset != s->l1_table_offset) {
l1_table = g_try_malloc0(align_offset(l1_size2, 512));
if (l1_size2 && l1_table == NULL) {
ret = -ENOMEM;
goto fail;
}
l1_allocated = true;
ret = bdrv_pread(bs->file->bs, l1_table_offset, l1_table, l1_size2);
if (ret < 0) {
goto fail;
}
for(i = 0;i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
} else {
assert(l1_size == s->l1_size);
l1_table = s->l1_table;
l1_allocated = false;
}
for(i = 0; i < l1_size; i++) {
l2_offset = l1_table[i];
if (l2_offset) {
old_l2_offset = l2_offset;
l2_offset &= L1E_OFFSET_MASK;
if (offset_into_cluster(s, l2_offset)) {
qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#"
PRIx64 " unaligned (L1 index: %#x)",
l2_offset, i);
ret = -EIO;
goto fail;
}
ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
(void**) &l2_table);
if (ret < 0) {
goto fail;
}
for(j = 0; j < s->l2_size; j++) {
uint64_t cluster_index;
offset = be64_to_cpu(l2_table[j]);
old_offset = offset;
offset &= ~QCOW_OFLAG_COPIED;
switch (qcow2_get_cluster_type(offset)) {
case QCOW2_CLUSTER_COMPRESSED:
nb_csectors = ((offset >> s->csize_shift) &
s->csize_mask) + 1;
if (addend != 0) {
ret = update_refcount(bs,
(offset & s->cluster_offset_mask) & ~511,
nb_csectors * 512, abs(addend), addend < 0,
QCOW2_DISCARD_SNAPSHOT);
if (ret < 0) {
goto fail;
}
}
/* compressed clusters are never modified */
refcount = 2;
break;
case QCOW2_CLUSTER_NORMAL:
case QCOW2_CLUSTER_ZERO:
if (offset_into_cluster(s, offset & L2E_OFFSET_MASK)) {
qcow2_signal_corruption(bs, true, -1, -1, "Data "
"cluster offset %#llx "
"unaligned (L2 offset: %#"
PRIx64 ", L2 index: %#x)",
offset & L2E_OFFSET_MASK,
l2_offset, j);
ret = -EIO;
goto fail;
}
cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
if (!cluster_index) {
/* unallocated */
refcount = 0;
break;
}
if (addend != 0) {
ret = qcow2_update_cluster_refcount(bs,
cluster_index, abs(addend), addend < 0,
QCOW2_DISCARD_SNAPSHOT);
if (ret < 0) {
goto fail;
}
}
ret = qcow2_get_refcount(bs, cluster_index, &refcount);
if (ret < 0) {
goto fail;
}
break;
case QCOW2_CLUSTER_UNALLOCATED:
refcount = 0;
break;
default:
abort();
}
if (refcount == 1) {
offset |= QCOW_OFLAG_COPIED;
}
if (offset != old_offset) {
if (addend > 0) {
qcow2_cache_set_dependency(bs, s->l2_table_cache,
s->refcount_block_cache);
}
l2_table[j] = cpu_to_be64(offset);
qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache,
l2_table);
}
}
qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
if (addend != 0) {
ret = qcow2_update_cluster_refcount(bs, l2_offset >>
s->cluster_bits,
abs(addend), addend < 0,
QCOW2_DISCARD_SNAPSHOT);
if (ret < 0) {
goto fail;
}
}
ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
&refcount);
if (ret < 0) {
goto fail;
} else if (refcount == 1) {
l2_offset |= QCOW_OFLAG_COPIED;
}
if (l2_offset != old_l2_offset) {
l1_table[i] = l2_offset;
l1_modified = 1;
}
}
}
ret = bdrv_flush(bs);
fail:
if (l2_table) {
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
}
s->cache_discards = false;
qcow2_process_discards(bs, ret);
/* Update L1 only if it isn't deleted anyway (addend = -1) */
if (ret == 0 && addend >= 0 && l1_modified) {
for (i = 0; i < l1_size; i++) {
cpu_to_be64s(&l1_table[i]);
}
ret = bdrv_pwrite_sync(bs->file->bs, l1_table_offset,
l1_table, l1_size2);
for (i = 0; i < l1_size; i++) {
be64_to_cpus(&l1_table[i]);
}
}
if (l1_allocated)
g_free(l1_table);
return ret;
}
/*********************************************************/
/* refcount checking functions */
static size_t refcount_array_byte_size(BDRVQcow2State *s, uint64_t entries)
{
/* This assertion holds because there is no way we can address more than
* 2^(64 - 9) clusters at once (with cluster size 512 = 2^9, and because
* offsets have to be representable in bytes); due to every cluster
* corresponding to one refcount entry, we are well below that limit */
assert(entries < (UINT64_C(1) << (64 - 9)));
/* Thanks to the assertion this will not overflow, because
* s->refcount_order < 7.
* (note: x << s->refcount_order == x * s->refcount_bits) */
return DIV_ROUND_UP(entries << s->refcount_order, 8);
}
/**
* Reallocates *array so that it can hold new_size entries. *size must contain
* the current number of entries in *array. If the reallocation fails, *array
* and *size will not be modified and -errno will be returned. If the
* reallocation is successful, *array will be set to the new buffer, *size
* will be set to new_size and 0 will be returned. The size of the reallocated
* refcount array buffer will be aligned to a cluster boundary, and the newly
* allocated area will be zeroed.
*/
static int realloc_refcount_array(BDRVQcow2State *s, void **array,
int64_t *size, int64_t new_size)
{
int64_t old_byte_size, new_byte_size;
void *new_ptr;
/* Round to clusters so the array can be directly written to disk */
old_byte_size = size_to_clusters(s, refcount_array_byte_size(s, *size))
* s->cluster_size;
new_byte_size = size_to_clusters(s, refcount_array_byte_size(s, new_size))
* s->cluster_size;
if (new_byte_size == old_byte_size) {
*size = new_size;
return 0;
}
assert(new_byte_size > 0);
if (new_byte_size > SIZE_MAX) {
return -ENOMEM;
}
new_ptr = g_try_realloc(*array, new_byte_size);
if (!new_ptr) {
return -ENOMEM;
}
if (new_byte_size > old_byte_size) {
memset((char *)new_ptr + old_byte_size, 0,
new_byte_size - old_byte_size);
}
*array = new_ptr;
*size = new_size;
return 0;
}
/*
* Increases the refcount for a range of clusters in a given refcount table.
* This is used to construct a temporary refcount table out of L1 and L2 tables
* which can be compared to the refcount table saved in the image.
*
* Modifies the number of errors in res.
*/
static int inc_refcounts(BlockDriverState *bs,
BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size,
int64_t offset, int64_t size)
{
BDRVQcow2State *s = bs->opaque;
uint64_t start, last, cluster_offset, k, refcount;
int ret;
if (size <= 0) {
return 0;
}
start = start_of_cluster(s, offset);
last = start_of_cluster(s, offset + size - 1);
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size) {
k = cluster_offset >> s->cluster_bits;
if (k >= *refcount_table_size) {
ret = realloc_refcount_array(s, refcount_table,
refcount_table_size, k + 1);
if (ret < 0) {
res->check_errors++;
return ret;
}
}
refcount = s->get_refcount(*refcount_table, k);
if (refcount == s->refcount_max) {
fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
"\n", cluster_offset);
res->corruptions++;
continue;
}
s->set_refcount(*refcount_table, k, refcount + 1);
}
return 0;
}
/* Flags for check_refcounts_l1() and check_refcounts_l2() */
enum {
CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */
};
/*
* Increases the refcount in the given refcount table for the all clusters
* referenced in the L2 table. While doing so, performs some checks on L2
* entries.
*
* Returns the number of errors found by the checks or -errno if an internal
* error occurred.
*/
static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size, int64_t l2_offset,
int flags)
{
BDRVQcow2State *s = bs->opaque;
uint64_t *l2_table, l2_entry;
uint64_t next_contiguous_offset = 0;
int i, l2_size, nb_csectors, ret;
/* Read L2 table from disk */
l2_size = s->l2_size * sizeof(uint64_t);
l2_table = g_malloc(l2_size);
ret = bdrv_pread(bs->file->bs, l2_offset, l2_table, l2_size);
if (ret < 0) {
fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n");
res->check_errors++;
goto fail;
}
/* Do the actual checks */
for(i = 0; i < s->l2_size; i++) {
l2_entry = be64_to_cpu(l2_table[i]);
switch (qcow2_get_cluster_type(l2_entry)) {
case QCOW2_CLUSTER_COMPRESSED:
/* Compressed clusters don't have QCOW_OFLAG_COPIED */
if (l2_entry & QCOW_OFLAG_COPIED) {
fprintf(stderr, "ERROR: cluster %" PRId64 ": "
"copied flag must never be set for compressed "
"clusters\n", l2_entry >> s->cluster_bits);
l2_entry &= ~QCOW_OFLAG_COPIED;
res->corruptions++;
}
/* Mark cluster as used */
nb_csectors = ((l2_entry >> s->csize_shift) &
s->csize_mask) + 1;
l2_entry &= s->cluster_offset_mask;
ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
l2_entry & ~511, nb_csectors * 512);
if (ret < 0) {
goto fail;
}
if (flags & CHECK_FRAG_INFO) {
res->bfi.allocated_clusters++;
res->bfi.compressed_clusters++;
/* Compressed clusters are fragmented by nature. Since they
* take up sub-sector space but we only have sector granularity
* I/O we need to re-read the same sectors even for adjacent
* compressed clusters.
*/
res->bfi.fragmented_clusters++;
}
break;
case QCOW2_CLUSTER_ZERO:
if ((l2_entry & L2E_OFFSET_MASK) == 0) {
break;
}
/* fall through */
case QCOW2_CLUSTER_NORMAL:
{
uint64_t offset = l2_entry & L2E_OFFSET_MASK;
if (flags & CHECK_FRAG_INFO) {
res->bfi.allocated_clusters++;
if (next_contiguous_offset &&
offset != next_contiguous_offset) {
res->bfi.fragmented_clusters++;
}
next_contiguous_offset = offset + s->cluster_size;
}
/* Mark cluster as used */
ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
offset, s->cluster_size);
if (ret < 0) {
goto fail;
}
/* Correct offsets are cluster aligned */
if (offset_into_cluster(s, offset)) {
fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
"properly aligned; L2 entry corrupted.\n", offset);
res->corruptions++;
}
break;
}
case QCOW2_CLUSTER_UNALLOCATED:
break;
default:
abort();
}
}
g_free(l2_table);
return 0;
fail:
g_free(l2_table);
return ret;
}
/*
* Increases the refcount for the L1 table, its L2 tables and all referenced
* clusters in the given refcount table. While doing so, performs some checks
* on L1 and L2 entries.
*
* Returns the number of errors found by the checks or -errno if an internal
* error occurred.
*/
static int check_refcounts_l1(BlockDriverState *bs,
BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size,
int64_t l1_table_offset, int l1_size,
int flags)
{
BDRVQcow2State *s = bs->opaque;
uint64_t *l1_table = NULL, l2_offset, l1_size2;
int i, ret;
l1_size2 = l1_size * sizeof(uint64_t);
/* Mark L1 table as used */
ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
l1_table_offset, l1_size2);
if (ret < 0) {
goto fail;
}
/* Read L1 table entries from disk */
if (l1_size2 > 0) {
l1_table = g_try_malloc(l1_size2);
if (l1_table == NULL) {
ret = -ENOMEM;
res->check_errors++;
goto fail;
}
ret = bdrv_pread(bs->file->bs, l1_table_offset, l1_table, l1_size2);
if (ret < 0) {
fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
res->check_errors++;
goto fail;
}
for(i = 0;i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
}
/* Do the actual checks */
for(i = 0; i < l1_size; i++) {
l2_offset = l1_table[i];
if (l2_offset) {
/* Mark L2 table as used */
l2_offset &= L1E_OFFSET_MASK;
ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
l2_offset, s->cluster_size);
if (ret < 0) {
goto fail;
}
/* L2 tables are cluster aligned */
if (offset_into_cluster(s, l2_offset)) {
fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not "
"cluster aligned; L1 entry corrupted\n", l2_offset);
res->corruptions++;
}
/* Process and check L2 entries */
ret = check_refcounts_l2(bs, res, refcount_table,
refcount_table_size, l2_offset, flags);
if (ret < 0) {
goto fail;
}
}
}
g_free(l1_table);
return 0;
fail:
g_free(l1_table);
return ret;
}
/*
* Checks the OFLAG_COPIED flag for all L1 and L2 entries.
*
* This function does not print an error message nor does it increment
* check_errors if qcow2_get_refcount fails (this is because such an error will
* have been already detected and sufficiently signaled by the calling function
* (qcow2_check_refcounts) by the time this function is called).
*/
static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix)
{
BDRVQcow2State *s = bs->opaque;
uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size);
int ret;
uint64_t refcount;
int i, j;
for (i = 0; i < s->l1_size; i++) {
uint64_t l1_entry = s->l1_table[i];
uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK;
bool l2_dirty = false;
if (!l2_offset) {
continue;
}
ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
&refcount);
if (ret < 0) {
/* don't print message nor increment check_errors */
continue;
}
if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
"l1_entry=%" PRIx64 " refcount=%" PRIu64 "\n",
fix & BDRV_FIX_ERRORS ? "Repairing" :
"ERROR",
i, l1_entry, refcount);
if (fix & BDRV_FIX_ERRORS) {
s->l1_table[i] = refcount == 1
? l1_entry | QCOW_OFLAG_COPIED
: l1_entry & ~QCOW_OFLAG_COPIED;
ret = qcow2_write_l1_entry(bs, i);
if (ret < 0) {
res->check_errors++;
goto fail;
}
res->corruptions_fixed++;
} else {
res->corruptions++;
}
}
ret = bdrv_pread(bs->file->bs, l2_offset, l2_table,
s->l2_size * sizeof(uint64_t));
if (ret < 0) {
fprintf(stderr, "ERROR: Could not read L2 table: %s\n",
strerror(-ret));
res->check_errors++;
goto fail;
}
for (j = 0; j < s->l2_size; j++) {
uint64_t l2_entry = be64_to_cpu(l2_table[j]);
uint64_t data_offset = l2_entry & L2E_OFFSET_MASK;
int cluster_type = qcow2_get_cluster_type(l2_entry);
if ((cluster_type == QCOW2_CLUSTER_NORMAL) ||
((cluster_type == QCOW2_CLUSTER_ZERO) && (data_offset != 0))) {
ret = qcow2_get_refcount(bs,
data_offset >> s->cluster_bits,
&refcount);
if (ret < 0) {
/* don't print message nor increment check_errors */
continue;
}
if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "%s OFLAG_COPIED data cluster: "
"l2_entry=%" PRIx64 " refcount=%" PRIu64 "\n",
fix & BDRV_FIX_ERRORS ? "Repairing" :
"ERROR",
l2_entry, refcount);
if (fix & BDRV_FIX_ERRORS) {
l2_table[j] = cpu_to_be64(refcount == 1
? l2_entry | QCOW_OFLAG_COPIED
: l2_entry & ~QCOW_OFLAG_COPIED);
l2_dirty = true;
res->corruptions_fixed++;
} else {
res->corruptions++;
}
}
}
}
if (l2_dirty) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2,
l2_offset, s->cluster_size);
if (ret < 0) {
fprintf(stderr, "ERROR: Could not write L2 table; metadata "
"overlap check failed: %s\n", strerror(-ret));
res->check_errors++;
goto fail;
}
ret = bdrv_pwrite(bs->file->bs, l2_offset, l2_table,
s->cluster_size);
if (ret < 0) {
fprintf(stderr, "ERROR: Could not write L2 table: %s\n",
strerror(-ret));
res->check_errors++;
goto fail;
}
}
}
ret = 0;
fail:
qemu_vfree(l2_table);
return ret;
}
/*
* Checks consistency of refblocks and accounts for each refblock in
* *refcount_table.
*/
static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix, bool *rebuild,
void **refcount_table, int64_t *nb_clusters)
{
BDRVQcow2State *s = bs->opaque;
int64_t i, size;
int ret;
for(i = 0; i < s->refcount_table_size; i++) {
uint64_t offset, cluster;
offset = s->refcount_table[i];
cluster = offset >> s->cluster_bits;
/* Refcount blocks are cluster aligned */
if (offset_into_cluster(s, offset)) {
fprintf(stderr, "ERROR refcount block %" PRId64 " is not "
"cluster aligned; refcount table entry corrupted\n", i);
res->corruptions++;
*rebuild = true;
continue;
}
if (cluster >= *nb_clusters) {
fprintf(stderr, "%s refcount block %" PRId64 " is outside image\n",
fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i);
if (fix & BDRV_FIX_ERRORS) {
int64_t new_nb_clusters;
if (offset > INT64_MAX - s->cluster_size) {
ret = -EINVAL;
goto resize_fail;
}
ret = bdrv_truncate(bs->file->bs, offset + s->cluster_size);
if (ret < 0) {
goto resize_fail;
}
size = bdrv_getlength(bs->file->bs);
if (size < 0) {
ret = size;
goto resize_fail;
}
new_nb_clusters = size_to_clusters(s, size);
assert(new_nb_clusters >= *nb_clusters);
ret = realloc_refcount_array(s, refcount_table,
nb_clusters, new_nb_clusters);
if (ret < 0) {
res->check_errors++;
return ret;
}
if (cluster >= *nb_clusters) {
ret = -EINVAL;
goto resize_fail;
}
res->corruptions_fixed++;
ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
offset, s->cluster_size);
if (ret < 0) {
return ret;
}
/* No need to check whether the refcount is now greater than 1:
* This area was just allocated and zeroed, so it can only be
* exactly 1 after inc_refcounts() */
continue;
resize_fail:
res->corruptions++;
*rebuild = true;
fprintf(stderr, "ERROR could not resize image: %s\n",
strerror(-ret));
} else {
res->corruptions++;
}
continue;
}
if (offset != 0) {
ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
offset, s->cluster_size);
if (ret < 0) {
return ret;
}
if (s->get_refcount(*refcount_table, cluster) != 1) {
fprintf(stderr, "ERROR refcount block %" PRId64
" refcount=%" PRIu64 "\n", i,
s->get_refcount(*refcount_table, cluster));
res->corruptions++;
*rebuild = true;
}
}
}
return 0;
}
/*
* Calculates an in-memory refcount table.
*/
static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix, bool *rebuild,
void **refcount_table, int64_t *nb_clusters)
{
BDRVQcow2State *s = bs->opaque;
int64_t i;
QCowSnapshot *sn;
int ret;
if (!*refcount_table) {
int64_t old_size = 0;
ret = realloc_refcount_array(s, refcount_table,
&old_size, *nb_clusters);
if (ret < 0) {
res->check_errors++;
return ret;
}
}
/* header */
ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
0, s->cluster_size);
if (ret < 0) {
return ret;
}
/* current L1 table */
ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
s->l1_table_offset, s->l1_size, CHECK_FRAG_INFO);
if (ret < 0) {
return ret;
}
/* snapshots */
for (i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
sn->l1_table_offset, sn->l1_size, 0);
if (ret < 0) {
return ret;
}
}
ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
s->snapshots_offset, s->snapshots_size);
if (ret < 0) {
return ret;
}
/* refcount data */
ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
s->refcount_table_offset,
s->refcount_table_size * sizeof(uint64_t));
if (ret < 0) {
return ret;
}
return check_refblocks(bs, res, fix, rebuild, refcount_table, nb_clusters);
}
/*
* Compares the actual reference count for each cluster in the image against the
* refcount as reported by the refcount structures on-disk.
*/
static void compare_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix, bool *rebuild,
int64_t *highest_cluster,
void *refcount_table, int64_t nb_clusters)
{
BDRVQcow2State *s = bs->opaque;
int64_t i;
uint64_t refcount1, refcount2;
int ret;
for (i = 0, *highest_cluster = 0; i < nb_clusters; i++) {
ret = qcow2_get_refcount(bs, i, &refcount1);
if (ret < 0) {
fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n",
i, strerror(-ret));
res->check_errors++;
continue;
}
refcount2 = s->get_refcount(refcount_table, i);
if (refcount1 > 0 || refcount2 > 0) {
*highest_cluster = i;
}
if (refcount1 != refcount2) {
/* Check if we're allowed to fix the mismatch */
int *num_fixed = NULL;
if (refcount1 == 0) {
*rebuild = true;
} else if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) {
num_fixed = &res->leaks_fixed;
} else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) {
num_fixed = &res->corruptions_fixed;
}
fprintf(stderr, "%s cluster %" PRId64 " refcount=%" PRIu64
" reference=%" PRIu64 "\n",
num_fixed != NULL ? "Repairing" :
refcount1 < refcount2 ? "ERROR" :
"Leaked",
i, refcount1, refcount2);
if (num_fixed) {
ret = update_refcount(bs, i << s->cluster_bits, 1,
refcount_diff(refcount1, refcount2),
refcount1 > refcount2,
QCOW2_DISCARD_ALWAYS);
if (ret >= 0) {
(*num_fixed)++;
continue;
}
}
/* And if we couldn't, print an error */
if (refcount1 < refcount2) {
res->corruptions++;
} else {
res->leaks++;
}
}
}
}
/*
* Allocates clusters using an in-memory refcount table (IMRT) in contrast to
* the on-disk refcount structures.
*
* On input, *first_free_cluster tells where to start looking, and need not
* actually be a free cluster; the returned offset will not be before that
* cluster. On output, *first_free_cluster points to the first gap found, even
* if that gap was too small to be used as the returned offset.
*
* Note that *first_free_cluster is a cluster index whereas the return value is
* an offset.
*/
static int64_t alloc_clusters_imrt(BlockDriverState *bs,
int cluster_count,
void **refcount_table,
int64_t *imrt_nb_clusters,
int64_t *first_free_cluster)
{
BDRVQcow2State *s = bs->opaque;
int64_t cluster = *first_free_cluster, i;
bool first_gap = true;
int contiguous_free_clusters;
int ret;
/* Starting at *first_free_cluster, find a range of at least cluster_count
* continuously free clusters */
for (contiguous_free_clusters = 0;
cluster < *imrt_nb_clusters &&
contiguous_free_clusters < cluster_count;
cluster++)
{
if (!s->get_refcount(*refcount_table, cluster)) {
contiguous_free_clusters++;
if (first_gap) {
/* If this is the first free cluster found, update
* *first_free_cluster accordingly */
*first_free_cluster = cluster;
first_gap = false;
}
} else if (contiguous_free_clusters) {
contiguous_free_clusters = 0;
}
}
/* If contiguous_free_clusters is greater than zero, it contains the number
* of continuously free clusters until the current cluster; the first free
* cluster in the current "gap" is therefore
* cluster - contiguous_free_clusters */
/* If no such range could be found, grow the in-memory refcount table
* accordingly to append free clusters at the end of the image */
if (contiguous_free_clusters < cluster_count) {
/* contiguous_free_clusters clusters are already empty at the image end;
* we need cluster_count clusters; therefore, we have to allocate
* cluster_count - contiguous_free_clusters new clusters at the end of
* the image (which is the current value of cluster; note that cluster
* may exceed old_imrt_nb_clusters if *first_free_cluster pointed beyond
* the image end) */
ret = realloc_refcount_array(s, refcount_table, imrt_nb_clusters,
cluster + cluster_count
- contiguous_free_clusters);
if (ret < 0) {
return ret;
}
}
/* Go back to the first free cluster */
cluster -= contiguous_free_clusters;
for (i = 0; i < cluster_count; i++) {
s->set_refcount(*refcount_table, cluster + i, 1);
}
return cluster << s->cluster_bits;
}
/*
* Creates a new refcount structure based solely on the in-memory information
* given through *refcount_table. All necessary allocations will be reflected
* in that array.
*
* On success, the old refcount structure is leaked (it will be covered by the
* new refcount structure).
*/
static int rebuild_refcount_structure(BlockDriverState *bs,
BdrvCheckResult *res,
void **refcount_table,
int64_t *nb_clusters)
{
BDRVQcow2State *s = bs->opaque;
int64_t first_free_cluster = 0, reftable_offset = -1, cluster = 0;
int64_t refblock_offset, refblock_start, refblock_index;
uint32_t reftable_size = 0;
uint64_t *on_disk_reftable = NULL;
void *on_disk_refblock;
int ret = 0;
struct {
uint64_t reftable_offset;
uint32_t reftable_clusters;
} QEMU_PACKED reftable_offset_and_clusters;
qcow2_cache_empty(bs, s->refcount_block_cache);
write_refblocks:
for (; cluster < *nb_clusters; cluster++) {
if (!s->get_refcount(*refcount_table, cluster)) {
continue;
}
refblock_index = cluster >> s->refcount_block_bits;
refblock_start = refblock_index << s->refcount_block_bits;
/* Don't allocate a cluster in a refblock already written to disk */
if (first_free_cluster < refblock_start) {
first_free_cluster = refblock_start;
}
refblock_offset = alloc_clusters_imrt(bs, 1, refcount_table,
nb_clusters, &first_free_cluster);
if (refblock_offset < 0) {
fprintf(stderr, "ERROR allocating refblock: %s\n",
strerror(-refblock_offset));
res->check_errors++;
ret = refblock_offset;
goto fail;
}
if (reftable_size <= refblock_index) {
uint32_t old_reftable_size = reftable_size;
uint64_t *new_on_disk_reftable;
reftable_size = ROUND_UP((refblock_index + 1) * sizeof(uint64_t),
s->cluster_size) / sizeof(uint64_t);
new_on_disk_reftable = g_try_realloc(on_disk_reftable,
reftable_size *
sizeof(uint64_t));
if (!new_on_disk_reftable) {
res->check_errors++;
ret = -ENOMEM;
goto fail;
}
on_disk_reftable = new_on_disk_reftable;
memset(on_disk_reftable + old_reftable_size, 0,
(reftable_size - old_reftable_size) * sizeof(uint64_t));
/* The offset we have for the reftable is now no longer valid;
* this will leak that range, but we can easily fix that by running
* a leak-fixing check after this rebuild operation */
reftable_offset = -1;
}
on_disk_reftable[refblock_index] = refblock_offset;
/* If this is apparently the last refblock (for now), try to squeeze the
* reftable in */
if (refblock_index == (*nb_clusters - 1) >> s->refcount_block_bits &&
reftable_offset < 0)
{
uint64_t reftable_clusters = size_to_clusters(s, reftable_size *
sizeof(uint64_t));
reftable_offset = alloc_clusters_imrt(bs, reftable_clusters,
refcount_table, nb_clusters,
&first_free_cluster);
if (reftable_offset < 0) {
fprintf(stderr, "ERROR allocating reftable: %s\n",
strerror(-reftable_offset));
res->check_errors++;
ret = reftable_offset;
goto fail;
}
}
ret = qcow2_pre_write_overlap_check(bs, 0, refblock_offset,
s->cluster_size);
if (ret < 0) {
fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
goto fail;
}
/* The size of *refcount_table is always cluster-aligned, therefore the
* write operation will not overflow */
on_disk_refblock = (void *)((char *) *refcount_table +
refblock_index * s->cluster_size);
ret = bdrv_write(bs->file->bs, refblock_offset / BDRV_SECTOR_SIZE,
on_disk_refblock, s->cluster_sectors);
if (ret < 0) {
fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
goto fail;
}
/* Go to the end of this refblock */
cluster = refblock_start + s->refcount_block_size - 1;
}
if (reftable_offset < 0) {
uint64_t post_refblock_start, reftable_clusters;
post_refblock_start = ROUND_UP(*nb_clusters, s->refcount_block_size);
reftable_clusters = size_to_clusters(s,
reftable_size * sizeof(uint64_t));
/* Not pretty but simple */
if (first_free_cluster < post_refblock_start) {
first_free_cluster = post_refblock_start;
}
reftable_offset = alloc_clusters_imrt(bs, reftable_clusters,
refcount_table, nb_clusters,
&first_free_cluster);
if (reftable_offset < 0) {
fprintf(stderr, "ERROR allocating reftable: %s\n",
strerror(-reftable_offset));
res->check_errors++;
ret = reftable_offset;
goto fail;
}
goto write_refblocks;
}
assert(on_disk_reftable);
for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) {
cpu_to_be64s(&on_disk_reftable[refblock_index]);
}
ret = qcow2_pre_write_overlap_check(bs, 0, reftable_offset,
reftable_size * sizeof(uint64_t));
if (ret < 0) {
fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret));
goto fail;
}
assert(reftable_size < INT_MAX / sizeof(uint64_t));
ret = bdrv_pwrite(bs->file->bs, reftable_offset, on_disk_reftable,
reftable_size * sizeof(uint64_t));
if (ret < 0) {
fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret));
goto fail;
}
/* Enter new reftable into the image header */
cpu_to_be64w(&reftable_offset_and_clusters.reftable_offset,
reftable_offset);
cpu_to_be32w(&reftable_offset_and_clusters.reftable_clusters,
size_to_clusters(s, reftable_size * sizeof(uint64_t)));
ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader,
refcount_table_offset),
&reftable_offset_and_clusters,
sizeof(reftable_offset_and_clusters));
if (ret < 0) {
fprintf(stderr, "ERROR setting reftable: %s\n", strerror(-ret));
goto fail;
}
for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) {
be64_to_cpus(&on_disk_reftable[refblock_index]);
}
s->refcount_table = on_disk_reftable;
s->refcount_table_offset = reftable_offset;
s->refcount_table_size = reftable_size;
return 0;
fail:
g_free(on_disk_reftable);
return ret;
}
/*
* Checks an image for refcount consistency.
*
* Returns 0 if no errors are found, the number of errors in case the image is
* detected as corrupted, and -errno when an internal error occurred.
*/
int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix)
{
BDRVQcow2State *s = bs->opaque;
BdrvCheckResult pre_compare_res;
int64_t size, highest_cluster, nb_clusters;
void *refcount_table = NULL;
bool rebuild = false;
int ret;
size = bdrv_getlength(bs->file->bs);
if (size < 0) {
res->check_errors++;
return size;
}
nb_clusters = size_to_clusters(s, size);
if (nb_clusters > INT_MAX) {
res->check_errors++;
return -EFBIG;
}
res->bfi.total_clusters =
size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE);
ret = calculate_refcounts(bs, res, fix, &rebuild, &refcount_table,
&nb_clusters);
if (ret < 0) {
goto fail;
}
/* In case we don't need to rebuild the refcount structure (but want to fix
* something), this function is immediately called again, in which case the
* result should be ignored */
pre_compare_res = *res;
compare_refcounts(bs, res, 0, &rebuild, &highest_cluster, refcount_table,
nb_clusters);
if (rebuild && (fix & BDRV_FIX_ERRORS)) {
BdrvCheckResult old_res = *res;
int fresh_leaks = 0;
fprintf(stderr, "Rebuilding refcount structure\n");
ret = rebuild_refcount_structure(bs, res, &refcount_table,
&nb_clusters);
if (ret < 0) {
goto fail;
}
res->corruptions = 0;
res->leaks = 0;
/* Because the old reftable has been exchanged for a new one the
* references have to be recalculated */
rebuild = false;
memset(refcount_table, 0, refcount_array_byte_size(s, nb_clusters));
ret = calculate_refcounts(bs, res, 0, &rebuild, &refcount_table,
&nb_clusters);
if (ret < 0) {
goto fail;
}
if (fix & BDRV_FIX_LEAKS) {
/* The old refcount structures are now leaked, fix it; the result
* can be ignored, aside from leaks which were introduced by
* rebuild_refcount_structure() that could not be fixed */
BdrvCheckResult saved_res = *res;
*res = (BdrvCheckResult){ 0 };
compare_refcounts(bs, res, BDRV_FIX_LEAKS, &rebuild,
&highest_cluster, refcount_table, nb_clusters);
if (rebuild) {
fprintf(stderr, "ERROR rebuilt refcount structure is still "
"broken\n");
}
/* Any leaks accounted for here were introduced by
* rebuild_refcount_structure() because that function has created a
* new refcount structure from scratch */
fresh_leaks = res->leaks;
*res = saved_res;
}
if (res->corruptions < old_res.corruptions) {
res->corruptions_fixed += old_res.corruptions - res->corruptions;
}
if (res->leaks < old_res.leaks) {
res->leaks_fixed += old_res.leaks - res->leaks;
}
res->leaks += fresh_leaks;
} else if (fix) {
if (rebuild) {
fprintf(stderr, "ERROR need to rebuild refcount structures\n");
res->check_errors++;
ret = -EIO;
goto fail;
}
if (res->leaks || res->corruptions) {
*res = pre_compare_res;
compare_refcounts(bs, res, fix, &rebuild, &highest_cluster,
refcount_table, nb_clusters);
}
}
/* check OFLAG_COPIED */
ret = check_oflag_copied(bs, res, fix);
if (ret < 0) {
goto fail;
}
res->image_end_offset = (highest_cluster + 1) * s->cluster_size;
ret = 0;
fail:
g_free(refcount_table);
return ret;
}
#define overlaps_with(ofs, sz) \
ranges_overlap(offset, size, ofs, sz)
/*
* Checks if the given offset into the image file is actually free to use by
* looking for overlaps with important metadata sections (L1/L2 tables etc.),
* i.e. a sanity check without relying on the refcount tables.
*
* The ign parameter specifies what checks not to perform (being a bitmask of
* QCow2MetadataOverlap values), i.e., what sections to ignore.
*
* Returns:
* - 0 if writing to this offset will not affect the mentioned metadata
* - a positive QCow2MetadataOverlap value indicating one overlapping section
* - a negative value (-errno) indicating an error while performing a check,
* e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2
*/
int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
int64_t size)
{
BDRVQcow2State *s = bs->opaque;
int chk = s->overlap_check & ~ign;
int i, j;
if (!size) {
return 0;
}
if (chk & QCOW2_OL_MAIN_HEADER) {
if (offset < s->cluster_size) {
return QCOW2_OL_MAIN_HEADER;
}
}
/* align range to test to cluster boundaries */
size = align_offset(offset_into_cluster(s, offset) + size, s->cluster_size);
offset = start_of_cluster(s, offset);
if ((chk & QCOW2_OL_ACTIVE_L1) && s->l1_size) {
if (overlaps_with(s->l1_table_offset, s->l1_size * sizeof(uint64_t))) {
return QCOW2_OL_ACTIVE_L1;
}
}
if ((chk & QCOW2_OL_REFCOUNT_TABLE) && s->refcount_table_size) {
if (overlaps_with(s->refcount_table_offset,
s->refcount_table_size * sizeof(uint64_t))) {
return QCOW2_OL_REFCOUNT_TABLE;
}
}
if ((chk & QCOW2_OL_SNAPSHOT_TABLE) && s->snapshots_size) {
if (overlaps_with(s->snapshots_offset, s->snapshots_size)) {
return QCOW2_OL_SNAPSHOT_TABLE;
}
}
if ((chk & QCOW2_OL_INACTIVE_L1) && s->snapshots) {
for (i = 0; i < s->nb_snapshots; i++) {
if (s->snapshots[i].l1_size &&
overlaps_with(s->snapshots[i].l1_table_offset,
s->snapshots[i].l1_size * sizeof(uint64_t))) {
return QCOW2_OL_INACTIVE_L1;
}
}
}
if ((chk & QCOW2_OL_ACTIVE_L2) && s->l1_table) {
for (i = 0; i < s->l1_size; i++) {
if ((s->l1_table[i] & L1E_OFFSET_MASK) &&
overlaps_with(s->l1_table[i] & L1E_OFFSET_MASK,
s->cluster_size)) {
return QCOW2_OL_ACTIVE_L2;
}
}
}
if ((chk & QCOW2_OL_REFCOUNT_BLOCK) && s->refcount_table) {
for (i = 0; i < s->refcount_table_size; i++) {
if ((s->refcount_table[i] & REFT_OFFSET_MASK) &&
overlaps_with(s->refcount_table[i] & REFT_OFFSET_MASK,
s->cluster_size)) {
return QCOW2_OL_REFCOUNT_BLOCK;
}
}
}
if ((chk & QCOW2_OL_INACTIVE_L2) && s->snapshots) {
for (i = 0; i < s->nb_snapshots; i++) {
uint64_t l1_ofs = s->snapshots[i].l1_table_offset;
uint32_t l1_sz = s->snapshots[i].l1_size;
uint64_t l1_sz2 = l1_sz * sizeof(uint64_t);
uint64_t *l1 = g_try_malloc(l1_sz2);
int ret;
if (l1_sz2 && l1 == NULL) {
return -ENOMEM;
}
ret = bdrv_pread(bs->file->bs, l1_ofs, l1, l1_sz2);
if (ret < 0) {
g_free(l1);
return ret;
}
for (j = 0; j < l1_sz; j++) {
uint64_t l2_ofs = be64_to_cpu(l1[j]) & L1E_OFFSET_MASK;
if (l2_ofs && overlaps_with(l2_ofs, s->cluster_size)) {
g_free(l1);
return QCOW2_OL_INACTIVE_L2;
}
}
g_free(l1);
}
}
return 0;
}
static const char *metadata_ol_names[] = {
[QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header",
[QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table",
[QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table",
[QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table",
[QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block",
[QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table",
[QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table",
[QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table",
};
/*
* First performs a check for metadata overlaps (through
* qcow2_check_metadata_overlap); if that fails with a negative value (error
* while performing a check), that value is returned. If an impending overlap
* is detected, the BDS will be made unusable, the qcow2 file marked corrupt
* and -EIO returned.
*
* Returns 0 if there were neither overlaps nor errors while checking for
* overlaps; or a negative value (-errno) on error.
*/
int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
int64_t size)
{
int ret = qcow2_check_metadata_overlap(bs, ign, offset, size);
if (ret < 0) {
return ret;
} else if (ret > 0) {
int metadata_ol_bitnr = ctz32(ret);
assert(metadata_ol_bitnr < QCOW2_OL_MAX_BITNR);
qcow2_signal_corruption(bs, true, offset, size, "Preventing invalid "
"write on metadata (overlaps with %s)",
metadata_ol_names[metadata_ol_bitnr]);
return -EIO;
}
return 0;
}
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